Lactoferrin, which is an iron binding protein present in milk and various secretions, has emerged as a multifunctionai protein involved in the host defense against infection and tumorogenesis. We have recently identified an alternative form of LF mRNA we term ALF. Although, we find ALF mRNA in 100% (30 of 30) normal human tissues, we find ALF mRNA in only 10% (3 of 28) diverse tumor-derived cell lines. In a preliminary study, we found lower levels of ALF mRNA in 90% (9 of 10) primary breast tumor specimens compared to normal human breast tissues. In Phase I, we plan to develop a quantitative RT-PCR assay for both LF and LF mRNA. We will then quantitatively examine levels of ALF and LF mRNA in 142 fully characterized, archived breast tumor specimens collected at Stanford University Hospital. We will then correlate our results to various clinical parameters including tumor grade, histology, presence or absence of estrogen receptors, and patient age. Care will be taken to ensure anonymity of tumor specimens. Measurement of ALF or LF mRNA may be useful as a molecular marker in breast cancer and may be beneficial choosing more aggressive surgical procedures, treatment options, or in determining prognosis. PROPOSED COMMERCIAL APPLICATION: If the proposed Phase I and Phase II study is successful, and ALF is established as a general Class II tumor-suppressor gene, a quantitative assay to measure ALF mRNA will be widely useful in basic research as a kit. Further, if ALF is an useful molecular marker for breast cancer, we would license the assay to the diagnostic community.